<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>布局及样式</title>
<style type="text/css">
h1{color:red;}
.kuang, .kuang2{
    border: 3px solid red;
    margin-bottom: 10px;
}
.kuang2{
    display: flex; /* 弹性布局 */
    flex-direction: row; /* 控制主轴的方向，默认就是row */
    align-items: center; /* 控制和主轴垂直方向元素的对齐方式 */
}
.item{
    border: 1px solid blue;
    margin: 10px;
}
span{color:blue;}
</style>
</head>
<body>
<h1>布局及样式</h1>
<div class='kuang'>
    <div class='item'>div1-块元素</div>
    <div class='item'>div2-块元素</div>
    <div class='item'>div3-块元素</div>
</div>
<div class='kuang2'>
    <div class='item'>
        <div>div1-块元素</div>
        <div>div1-块元素</div>
    </div>
    <div class='item'>
        <div>div2-块元素</div>
    </div>
    <div class='item'>
        <div>div3-块元素</div>
        <div>div3-块元素</div>
    </div>
</div>

</body>
</html>